Tire construction



Sept` 2, 1941. c. G. HOOVER i 2,254,778

y TIRE CONSTRUCTION Filed March 24, 1937 2 Sheets-Sheet'l f5. Il f f5f/U FHQ.

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TIRE CONSTRUTION Filed March 24, 1937 2 vsheets-Sheet 2 INVENTQR ZY/gzjgovgf BYv i I ATTO R-.N Ey

Patented Sept. 2, 1941 TIRE CONSTRUCTION Clair G. Hoover, Akron, Ohio,assignor to The"A Firestone Tire & Rubber Company, Akron, Ohio, acorporation of Ohio Application March 24, 1937, Serial N0. 132,755

1 Claim.

This invention relates to improvements in tire construction, and moreespecially it relates to improvements in the traction characteristics ofthe tread portion of pneumatic tires.

The chief objects of the invention are to provide a tire that will bequiet in operation; that will have good tractive qualities; and toprovide a tire tread wherein the tractive elements will not be subjectto excessive wear. Other objects will be manifest as the specificationproceeds.

Of the accompanying drawings:

Figure 1 is a developed plan View showing the pattern of the improvedtire tread;

Figure 2 is a perspective view of a tire casing comprising the improvedtread; and

Figure 3 is a section, on a larger scale, on the line 3 3 of Figure 2.

Referring to the drawings, there is shown at I Il a pneumatic tirecasing that has its outer peripheral region provided with a treadstructure comprising a plurality oi' continuous, parallel,circumierentially extending ribs. Said ribs are shown as six in number,those at the respective lateral margins of the tread being designatedII, II, those in the medial region of the tread immediately each side ofthe central plane of the tire being designated I2, I2, and thoseintermediate the ribs II, I2 being designated I3. The aforesaid ribs areseparated by continuous, circumferentially extending grooves I4, I4.

The shoulders I5, I5 of the tire casing slope from the outer lateralmargins of ribs II to the sidewalls of the tire, and said slopedsurfaces are formed with grooves I6, I6 and recesses II, I'I that definerecurring designs or characters around the tire on each side thereof.These designs give to the tire a distinctive, characteristic appearance.They are disposed entirely inwardly of the peripheral face of thetreadv4 but under some conditions, as in deep mud or snow, they mayprovide additional traction for the tire.

The individual designs or characters defined by the grooves I6 andrecesses Il are of two different sizes or widths, and are symmetricallydisposed about the tire according to a determinate arrangement, whicharrangement is such that the designs on one side of the tread never aretransversely aligned with those on the other side of the tread. Thearrangement is shown most clearly in Figures 1 and 2 wherein thatportion of the tread that lies between lines and z-z constitutes exactlyone-fourth of the total linear extent of the tread. The two differentsizes of sidewall characters are spaced diierently between adjacentcharacters, one spacing being indicated by the letters a and the otherspacing by the letters b, the letters a' and b indicating half-spaces.In the region between lines xand za, on each side of the tire, there are81/2 spaces a and 'l1/2 spaces b on each side of the tread, the seriesof spaces a on one side of the tread being opposite the series of spacesb on the other side of the tread. The asymmetrical arrangement of thelateral tire designs is such as to prevent resonance of sounds arisingfrom use of the tire, thereby making for quietness of operation.

To improve the tractve qualities of the ribs I I, I2, and I3, each ofthem is provided, on its side nearest the centerline of the tread, witha circumferential series of integral, laterally extending projections orlugs I9, I9. 'I'hese lugs preferably are wedge shape in plan, as shown,and extend part way across the grooves I4. The arrangement of the lugsI9 longitudinally of the ribs `bears a determinate relationship to thespacing of the lateral designs formed by the grooves I6 and recessesI'I. On each lateral rib II and intermediate rib I3 the lugs I9 arealigned with each space a and b of the designs on the same side of thetread. On each medial rib- I2 the lugs I9 are transversely aligned withthe lugs of adjacent ribs I3 and II, but are double spaced so as to bealigned only with alternate lugs on the latter. It will be seen that thelugs I9 of ribs I2 extend into the same groove I4, which groove isdisposed along the centerline of the tread, and that the spacing betweenadjacent lugs varies in extent according to a denite pattern, but thatthe lugs on opposite ribs I2 never are aligned with each other. Thearrangement provides the same lack of symmetry of the series of lugs onopposite sides of the centerline of the tread as exists in the designsdened by the grooves I6 and recesses I'I at each side of the tread, andthus results in quietness of operation.

The staggering and progressive variation in spacing of lugs I9 on theopposite sides of the centerline of the tread prevents the setting up ofobjectionable tones having periodic frequencies. Inasmuch as the slopingshoulders I5, I5 do not normally contact the road surface, the groovesI6, I Ii and recesses Il, I'I may be equally spaced if desired, yoromitted entirely, leaving only lugs IS, I9 in asymmetrical arrangement.

Another feature of the tread that makes for quietness of operation isthe absence of recesses or notches in the ribs on the opposite sides ofthe grooves from the lugs I9. In tire treads formed with such notchesthere is excessive wear and cupping of the ribs around the notches sothat the present construction results in improved Wear.

Another distinctive feature of the invention is the absence ofprojections or lugs on the sides of the ribs remote from the centerlineof the tread, al1 such lugs being directed toward said centerline. Thearrangement provides adequate traction and skid-resisting qualities, andavoids un dercutting which occurs on projections directed away from thecenterline of the tread, but does not occur on oppositely directed lugs.

Modication may be resorted to Without departing from the spirit of theinvention or the scope of the appended claim.

What is claimed is:

A tire structure comprising a tread portion that is formed with aplurality of circumferentially extending ground engaging ribs that areseparated by continuous intervening grooves, each rib being formedsolely on the lateral face thereof that is nearest the central plane ofthe tire with a circumferential series of Wedgeshaped lugs that extendpartly across a groove and have their apexes directed toward the plainsmooth lateral surface of the adjacent rib.

CLAIR G. HOOVER.

